21673573 has 2 divisors, whose sum is σ = 21673574. Its totient is φ = 21673572.

The previous prime is 21673559. The next prime is 21673577. The reversal of 21673573 is 37537612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19651489 + 2022084 = 4433^2 + 1422^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21673573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21673577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10836786 + 10836787.

It is an arithmetic number, because the mean of its divisors is an integer number (10836787).

Almost surely, 2^21673573 is an apocalyptic number.

It is an amenable number.

21673573 is a deficient number, since it is larger than the sum of its proper divisors (1).

21673573 is an equidigital number, since it uses as much as digits as its factorization.

21673573 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26460, while the sum is 34.

The square root of 21673573 is about 4655.4884813519. The cubic root of 21673573 is about 278.8111713298.

The spelling of 21673573 in words is "twenty-one million, six hundred seventy-three thousand, five hundred seventy-three".